The present invention relates to apparatus for opening signatures intended to be supplied to binding machines; in particular the invention relates to improved signature-opening apparatus capable of operating at a high rate.
As is known, for supplying certain types of binding machines, for example stitching machines, it is necessary first to open the signatures at their centre, and this must be done regardless of the number of sheets or additional tables of which the signatures themselves are composed. This operation is currently performed by means of machines equipped with suckers which operate by taking the individual signatures from a magazine and opening them sheet by sheet using the suckers until reaching the middle; the signatures are then disposed with the opening oriented downwardly straddling a saddle.
Such known machines, however, have certain functional disadvantages because of the delicacy of the operations which they perform. In particular, a major disadvantage is the limitation of the speed at which the signatures can be handled, which is imposed by the structure of the known machines and the way they operate. Any attempt to increase the speed of operation of currently known commercially available machines would result in an increase in the speed of movement of the suckers which lift the sheets and, therefore, an increase in the speed and violence with which the sheets are raised and folded back. In practice, therefore, the possibility of making the known machines operate faster is prevented by the mechanical and geometrical characteristics of the paper and the signatures, such as the direction of the fibres, defects in the flatness of the paper, warping and such like.